Fukushima tank leak may have mixed with groundwater, Tepco reckons

Highly radioactive water leaking from a storage tank at the crippled Fukushima No. 1 nuclear plant may have seeped into groundwater flowing toward the Pacific Ocean, Tokyo Electric Power Co. admitted Thursday.

It is the first time that Tepco has indicated that leaks from the tank — situated inland from the coastal reactors, three of which suffered meltdowns in March 2011 — could also be polluting the groundwater beneath the plant. Tepco has already admitted that radiation from the stricken reactors has contaminated groundwater flowing to the sea. It is believed about 300 tons of highly radioactive groundwater is entering the Pacific daily.

About 300 tons of highly radioactive water also leaked from one of around 1,000 storage tanks last month. Tepco earlier said it discovered the leak after the fact but was uncertain where most of the water went.

Tepco said Thursday that workers had detected radiation of 650 becquerels per liter in samples from a monitoring well dug near the damaged tank.

“There is the possibility that the contaminated water (from the tank), diluted by rainwater . . . has seeped into soil and reached groundwater,” Tepco said in a press release.

The groundwater from the surrounding mountains naturally flows beneath the plant toward the sea.

As it seeps through the soil it mixes with polluted water that has sunk into the ground under the reactors.

The government said Tuesday it would spend ¥47 billion on a scheme to freeze the soil around the stricken reactors to form an impenetrable wall of ice they hope will direct groundwater away from the plant.

Thousands of tons of radioactive water are being stored in the temporary tanks at Fukushima. Much of it has been used to cool the melted reactor cores.

The discovery of leaks from some of these tanks or from pipes feeding them, as well as radiation hot spots on the ground even where no water is evident, has created a growing sense of crisis.

In a minor incident, the arm of a 600-ton crane being used to remove debris at the plant was found to be bent down, Tepco said in another press release.

Plant workers confirmed that damage had been done to a part where the crane’s arm was connected to its main mast, the statement said.